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HOME POWER BACKUP SYSTEMS –

ELECTRICAL ENGINEERS ANSWER YOUR QUESTIONS

www.dailymaverick.co.za/article

South Africa’s electricity utility Eskom has made it clear that “load shedding” – rolling scheduled power cuts – isn’t going to end any time soon. This reality, and President Cyril Ramaphosa’s announcement during his annual state of the nation speech on 9 February 2023 that tax incentives for solar power use are imminent, mean that many people are considering alternative electricity supply systems for their homes.

But deciding on the best home power backup system isn’t a simple matter. There’s a bewildering array of jargon to sift through and many elements to consider, from the right kind of inverter to the size of your solar panels.

We are electrical engineers who are working on a standalone charger for small electric vehicles with the South African National Energy Development Institute as part of the Long-Term Joint European Union – African Union Research and Innovation Partnership on Renewable Energy. The way the charger is designed resembles the sort of system needed for domestic power cut solutions. So, we’re able to answer a few questions for those who feel overwhelmed by the options.

WHAT IS AN INVERTER?

This is a key component of any alternative power system. It’s an electronic device that changes direct current (like energy stored in a battery) into alternating current (power for your home).

There are a few kinds of inverters. Some are grid-tied (synchronous) with Eskom’s power grid. They are typically used with solar systems that augment the Eskom supply. But they are not suitable for load shedding solutions.

You also get off-grid (grid-forming) inverters, which form their own mini-grid and can operate during power cuts.

We recommend a hybrid inverter, which can be grid-tied to augment supply and seamlessly continue operation as an offgrid solution during load shedding. You want a hybrid inverter that can connect to the grid, battery backup, and to solar panels. To extract the maximum power from the solar panels, be sure to get one that has maximum power point tracking (MPPT).

WHAT SIZE SHOULD THE SYSTEM BE?

This purchase should be a long-term investment. The inverter must be able to carry the sum of all the loads that are drawing power at any instant in time and the battery must be able to supply the energy required.

To reduce both the upfront capital cost and operational expenditure, you need to decide what is essential. Lights? Your washing machine? The stove and electric kettle? Then you need to make sure they are as energy efficient as possible before you size the backup system. For example, old incandescent lights use ten times more energy than LED lights do.

This table lists a few typical household items and their power consumption.

This table lists a few typical household items and their power consumption. Table: MJ Booysen. Source: MJ Booysen.

Created with Datawrapper

Deciding on the best system isn’t a simple matter. There’s a bewildering array of jargon to sift through and many elements to consider.

WHY DO I NEED BATTERIES FOR MY SYSTEM?

It is theoretically possible for an inverter to generate electricity for household use directly from solar panels. But the supply from panels is intermittent and often not powerful enough to reliably supply power to the varying loads in the house.

To overcome this problem, energy is stored in the batteries. This provides a more stable source of power which responds to demand during load shedding.

Battery capacity is specified as kWh (kilowatt hours) or Ah (ampere hours). This determines the amount of energy it can supply. A battery with a capacity of 5kWh can theoretically supply 5kW for an hour. But if a lithium battery is discharged beyond 20% of its capacity, it loses capacity and ages faster. A 5kWh battery therefore has an effective capacity of only 4kWh. It can supply 4kW for one hour, or 1kW for four hours.

As a practical example, if you want to power only 20 10W LED lights and a medium-sized LED TV, drawing a total of 0.5kW, a 3.5kWh battery will suffice for four hours.

ARE SOLAR PANELS CRUCIAL FOR A BACKUP SYSTEM?

No. The batteries store energy to provide a stable supply to the inverter when needed. Technically, you can use the mains power to charge the batteries, rather than rely on solar panels. Solar panels are merely there to augment the supply of electricity and could give you a bit more range during load shedding if the sun is shining.

But if everyone installs backup systems without solar panels, we are just using batteries to carry us through power cuts. That increases the load on Eskom outside load shedding periods, as the batteries must be replenished. This will neuter Eskom’s ability to use load shedding as a grid management tool. It could destabilise the grid and lead to a complete blackout.

And if, as is expected, the finance minister introduces tax breaks for solar generation expenses in the budget speech on 22 February, solar panels will have to be part of your setup if you want to benefit from these incentives.

No matter what Enoch Godongwana announces, we think this is a good time to make the switch to a solar-powered backup system, for your peace of mind and future savings.

HOW MUCH DOES IT ALL COST?

Inverter prices are falling as the market grows, and vary across suppliers. Inverters cost about R3,000 per kW for bottom of the range, and closer to R7,000 per kW for top of the range. Most households will get by with a 3kW to 5kW inverter, if its loads are managed well, costing between R9,000 and R35,000.

Lithium (LiFePO4) batteries also vary in cost but normally retail for about R5,000 to R7,000 per kWh. Most households will get by with a 5kWh to 10kWh battery if the loads are optimised and managed well. So you’re looking at a cost of between R25,000 and R70,000 for the batteries.

Solar panels tend to range from R8,000 to R10,000 per kWp (a measure of how high the panels’ power output is). Again, they’re not crucial, but are necessary if you want the system to pay for itself over time.

CAN I INSTALL THIS SYSTEM MYSELF?

No, unless you’re a certified electrician. The inverter needs to be installed into the distribution board and the cost will depend on how many of your circuit breakers need to be moved to the backup as well as how easy the solution is to install; installation typically ranges from R10,000 to R20,000. The inverter must be approved by the municipality if you want to feed back into the grid. Installing the solar panels is separate, and costs vary widely. DM/ML

MJ (Thinus) Booysen is a Professor in Engineering and Chair in the Internet of Things at Stellenbosch University. Arnold Rix is a Senior Lecturer in Electronic and Electrical Engineering at Stellenbosch University.

A battery back-up inverter system in a residential building in the Hout Bay district of Cape Town, South Africa, on Friday, April 22, 2022. Image: Dwayne Senior / Bloomberg via Getty Images

BE AWARE OF BUYING ON SOCIAL MEDIA

Buying on social media has it pitfalls so be aware when making purchases. Not all the sellers and buyers on social media platforms are out to get you but many are

Many community members will be looking to advertise their sales and purchases online through platforms like Facebook marketplace and Gumtree.

Brighton Beach Police are investigating numerous cases of Fraud relating to these types of purchases and sales.

Tracking suspects who make use of fake user profiles, uber collections and drop offs as well as fraudulent banking confirmations make this a very difficult crime to combat as well as investigate.

From a combating point of view it is impossible to police private purchases and decisions regarding who a person sells to or buys from in the comfort of their own homes thus awareness of the prevalence of this type of crime is very important.

MARKETPLACE – SELLING AN ITEM

Check the buyers profile of items previous advertised, bought and sold is one way to establish if the person makes frequent sales and is reliable.

Their user profile number of friends and posts should indicate regular usage and what you need to know about the buyer. Few details and friends/ photos usually indicate a

new account. Ask for a copy of the buyers’ identity document, and details of the vehicle that will be used by the buyer when collecting the items. If you are being paid by bank transfer E wallet etc, make sure the correct amount of funds are cleared in your account before agreeing to the collection of the item. Do not allow the goods to leave with only banking confirmation by the buyer, check your account. Do not accept part payments.

If the buyer will indicates that they need to transfer the money as they are stuck at work/ car broken down etc and they will send an alternate person/ uber to collect the item, rather stick with your originally agreed to terms and cancel or delay the sale until the buyer can meet your original terms.  A serious buyer will not be deterred.

Any “last minute” changes to what you have agreed to with respect to the collection and or payment of the goods are concerning.

Always record the time and date of collection the Buyers name, ID Number, address, car make model colour and registration, contact numbers etc for your records. Hopefully you will never need them but if you later establish that you have been scammed this will assist Authorities in trying to trace the buyer.

BUYING:

If buying an item online check the seller’s profile.

See if the items being sold are not being sold by other parties on other social media groups (Photos) and check if the contact numbers are the same or different.

Always arrange to collect the item yourself and do not request the seller to post/ uber the item to you. Watch out for fake business profiles. See what they buy and sell, if they are regular suppliers.

Again be aware of any “Last Minute Changes” rather lose out on that particular item than your money.

BE AWARE OF FAKE ONLINE BUSINESSES.

DO SOME RESEARCH

Always record the time and date of collection.

Sellers name, ID Number, address, contact numbers etc for your records. Hopefully you will never need them but if you later establish that you have been scammed this will assist Authorities in trying to trace the buyer.

WARN AND PROTECT OTHER BUYERS

If you feel that you have averted being scammed please report the matter to the administrators of the Social media site  (block the profile). Also report this matter to the SAPS. Remember that scammers do this for a living and there will be buyers/ sellers out there not as aware as you are where the information you have collected could be useful.

DON’T LET LOADSHEDDING FRY YOUR PRECIOUS APPLIANCES

Loadshedding is hitting South African consumers right in their pockets. Since the current round of loadshedding started, insurer King Price has seen a 100% increase in the number of claims for damage caused to appliances due to power surges –and with Eskom running out of money to buy diesel in the coming months, as announced in its State of the System Presentation, things are only going to get worse.

That’s the warning from King Price Insurance’s client experience partner, Wynand van Vuuren, who says the company has settled more than R21 million in claims in the past 14 months alone, for damages sustained through power surges and dips affecting residential buildings, home contents and portable possessions. This figure excludes lightning-related and large commercial claims.

“We’re getting a massive number of claims for ‘fried’ computer equipment, fridges, TVs and even distribution boards caused by power surges,” said Van Vuuren. “But there are several steps you can take to avoid having to replace your expensive appliances.”

UNPLUG YOUR APPLIANCES

The easiest, cheapest and most effective way of protecting your appliances is simply to unplug them when you’re not using them, or when the power goes off. That way, you’re 100% protected from power surges, says Van Vuuren.

INSTALL A UPS SYSTEM

UPS (uninterruptable power supply) systems can go a long way towards protecting your most valuable appliances. A UPS enables your appliances to shut down properly when the power goes off, and it’ll protect them from the power surges that often occur when the power comes back on.

USE ALTERNATIVE POWER SUPPLIES SAFELY

INSTALL SURGE PROTECTION

The most effective surge protectors are connected directly to your distribution board by a qualified electrician. These protectors divert any excess power into a grounding wire. Another option is to use surge protector strips on all your plugs, which provide a certain level of protection against surges caused by the power coming back on after an outage, or by lightning strikes.

Alternative power supplies must comply with safety guidelines, and they must be installed by a registered electrician. Portable generators are relatively cheap and easy to operate but must be correctly linked to your power supply. Simply plugging a generator into a house plug is known as back-feeding and it’s not only dangerous, it may result in any damage not being covered by your insurer.

CHECK YOUR INSURANCE

It’s important to check your home contents insurance to see if you’re covered for damage from power surges, says Van Vuuren. In general, consumers should be able to claim these damages directly from their municipality, but this isn’t always viable. If you’re insured for electrical damage due to power surges and dips, you can claim directly from your insurer, who will then claim from the municipality on your behalf.

ANOTHER MAJOR SECURITY RISK FOR HOMES IN SOUTH AFRICA

Security company Fidelity ADT has warned homeowners to ensure their battery backups and security support systems are maintained during load shedding.

The group said that load shedding has knock-on effects on home security, and the increased frequency and duration of rolling blackouts in the country are causing damage to these systems.

Regular power cuts are impacting a range of technologies and communications systems, including alarm systems that start to malfunction without adequate battery backup, it said.

The group added that malfunctioning alarm systems increase false alarm activations, which, in turn, impact armed response’s ability to deal with real emergencies.

“Sufficient battery backups and charging capacity can extend the uptime of alarm systems during load shedding,” it said. The group noted, however, that it is not ideal for any battery to be faced with continuing bouts of power cuts –whether they are planned or unplanned.

According to Fidelity’s head of communications, Charnel Hattingh, batteries already play a big part in the home security system, including for electric fences and gate motors. While wireless security systems have batteries in the detectors that are not affected by load shedding, the main control box still contains a backup battery that should not be neglected, she said.

“When you check your backup batteries, make sure you look at everything. Preventative maintenance action today can help ensure that your security system still operates the way it should tomorrow,” said the head of communications.

According to Hattingh, batteries have a limited lifespan as they charge and discharge repeatedly.

Batteries that have gone through too many of these cycles deteriorate and may not be able to charge sufficiently during load-shedding times – compromising security systems.

Stage 1 load shedding can give batteries enough time to recharge; however, the higher stages place more pressure on batteries.

Hattingh added that armed response companies might alert homeowners of the potentially low batteries via SMS. Homeowners should ensure that alarm systems are working optimally, said Hattingh.

“Your security system’s keypad can

HEIGHTENED CRIME

Making home security a priority during South Africa’s near-permanent state of load shedding is vital, as the rolling blackouts provide the most opportune time for criminals in the country to act. Security experts and insurers recently warned that crime and claim data are pointing to elevated levels of crime in the country, attributing the spike to high levels of load shedding that have been in place since the start of the year.

Auto & General said that it has seen a 40% increase in the number of burglaries reported in the first two weeks of 2023 compared to the same period in 2022.

Speaking at a National Press Club briefing on load shedding security risks last week, security experts said blackouts were simply making South Africa’s already bad crime situation worse.

The warnings go hand-in-hand with alerts from major metros in the country, which have been placed on a high alert to tackle elevated levels of vandalism and theft of public infrastructure during load shedding.

provide you with information about any problems that need technical intervention. Search on the internet for a copy of the system’s user guide or ask your monitoring company to send you a copy.”

Hattingh said UPS backup systems are also useful to add to any home system, even if they are costly.

“They can play a part in keeping you and your property safe if they are connected properly and used in the way they were intended to be used.”

“The increases seem to be spiking as a result of load shedding. Load shedding is a very worrying factor that powers on to a number of other factors that weaken our public security situation and the ability of the state to effectively respond to that situation,” the security experts said.

The FINAL Word

South Africa is in a real pickle. We have chronic loadshedding, government infighting, rampant inflation, huge crime issues, strikes, national protests, massive unemployment with a third of the total population unemployed and of course corruption in every sphere of the government.

All of these do not seem to have any workable solutions with the ANC government more intent on protecting its majority than trying to help the country that it is supposed to serve. Cyril Ramaphosa has hailed the grant culture as the success of the ANCpaying pensioners 2000 rand a month, ladies to have babies and an allowance to 350 rand to ease the pain of day to day living. To put the R350 into perspective, a loaf of bread costs R10.35 loaves of bread a month that is what the grant buy.

The rising cost of fruit and vegetables have made these essentials luxury items. And this is the success of the ANC government

Since the governments indaba on Gender Based Violence in November-in which decisions that were taken have not been implemented - we had the 16 days of activism in December and has the GBV rate decreased?

Sadly not. In fact it has got worse. We have provinces in the country who have called for a national day of prayer to deal with this scourge.

There is also an uptake in human trafficking with police raiding brothels and discovering women being forced to work there. Now a new scourge has raised it’s ugly head. The kidnapping of successful business men and women as well as children and they are held for ransom. And the police seem to be powerless to do anything.

The murder of the rapper AKA in public was caught on video and so far no one has been held accountable and it’s looking less likely that the police will catch the culprits.

It seems very bleak for the country I can understand why so many people are leaving South Africa. The challenge for those of us that remain is what are we going to do about it? Wearing T shirts and having protest marches are not going to change anything- it might get a few clicks but that is about all. They say that a fish rots from the head down. So we need to deal with the head.

My desire is that the opposition parties stop their personal agendas and unite to form one party and save the country because what is likely to happen in the 2024 general election is the ANC will not get a majority and they will form a government with the EFF and Julius Malema gets his dream job President of South Africa

IT’S TIME TO WAKE UP

MARTYN SMITHERS

PICS CREDIT: Brandan Reynolds